The present invention relates to a printer having a digital image processing capability and, more particularly, to a printer capable of printing image data on a sheet of irregular size.
It is a common practice with a printer of the type described to provide keys on an operation panel which are accessible for printing :image data on sheets of regular sizes (e.g. A4, A3, B5 and B4) by menu selection. However, when a sheet of irregular size is used, the size thereof cannot be defined. In practice, therefore, it is impossible to deal with, e.g., a magnification change ratio for a sheet of irregular size by menu selection. It has been customary with a printer to determine the size of sheets by use of exclusive sheet cassettes of different sizes or a slidable sheet feed tray. A sheet size sensor built in a tray is another conventional implementation. However, sheet sizes are not sensed on a millimeter basis since sheets of irregular sizes are not expected to be often used. It follows that the operator intending to use a sheet of irregular size has to measure or estimate the size of a document and that of the sheet and then operate, e.g., the keys to enter the dimensions of the sheet or an adequate magnification change ratio.